FIG. 6.

Membranes from an H. pylori 1-phosphatase (hp0021) mutant require prior removal of the 1-phosphate group from Kdo₂-lipid A for Kdo hydrolase activity. The Kdo hydrolase activity of H. pylori membranes lacking a functional copy of hp0021 (1-phosphatase) was assayed using either 5 μM Kdo₂-[4′-³²P]lipid A (panel A) or 5 μM 1-dephosphorylated Kdo₂-[4′-³²P]lipid A (panel B). Assays were performed as described in Materials and Methods using 0.5 mg/ml of membranes for the indicated times. The reaction products were separated by TLC and subjected to PhosphorImager analysis. Panel C is a plot of Kdo hydrolase activity using the two substrates described above during a linear period of product formation.